The California drought will deprive the state's thirsty farmers of 6.6 million acre-feet of surface water, which works out to a whopping 2.2 trillion gallons — enough to fill 60 million average-sized swimming pools, a new study revealed. The drought is causing the "greatest absolute reduction in water availability for California agriculture ever seen," according to the study by the University of California at Davis.

Farmers are making up for some of this lost water by pumping as much groundwater as they can tap into, which will diminish the state's ability to withstand future droughts, the study, released Tuesday, said. Including 5.1 million acre-feet of groundwater withdrawals, the net water shortage will amount to 1.6 million acre-feet., or about 521 billion gallons.

In this May 1, 2014 photo, irrigation water runs along a dried-up ditch between rice farms in Richvale, California. In dry California, water is fetching record high prices.

Image: Jae C. Hong

The study found that the drought will cost California's agricultural sector $1.5 billion, including $1 billion in revenue losses and $0.5 billion for the electricity costs involved in extracting more groundwater. The total statewide cost of the 2014 drought will be $2.2 billion.

The study demonstrates that California needs to start monitoring and regulating the use of groundwater supplies, according to its authors, including U.C. Davis economist Richard Howitt. Currently, it is the only western state that doesn't even keep tabs on its supplies, let alone limit the amount that can be used.

Groundwater, unlike surface water, is not quickly replenished via rainfall, and is comparable to a retirement savings account. Once it's used up, it's not easily refilled. As groundwater supplies decline, the land in the Central Valley sinks, as measured by NASA satellites.

"We’re running down our bank account,” Howitt said. “We’re like somebody who is so rich that we don’t have to balance the checkbook ... we still think we’re in a groundwater-rich era.”

All of California is in some stage of drought, with 79% of the state suffering from "extreme" to "exceptional" drought conditions — the two worst categories — according to U.S. Drought Monitor data. The drought is among the worst short-term (one- to three-year droughts) on record, although evidence exists of severe droughts that lasted as long as several centuries, but those occurred well before modern records began.

Los Angeles has had its driest two rainy seasons during the past two years of any water years since records began there in 1877. (A water year is measured from July 1 to June 30.)

While most farms will be able to continue irrigating their fields through the use of groundwater, some farms will not, and the 5% of cropland that is going out of production in the Central Valley, Central Coast and southern California could cost about 17,000 seasonal and part-time jobs this year alone, the study found. This will lead to “pockets of extreme deprivation where we’re out of water and out of jobs,” Howitt said. “In certain parts of the Central Valley, it’s extremely bad.”

The hardest hit area, in terms of agricultural costs, is the Tulare Basin, where projected losses add up to $810 million.

Drought conditions cover the entire state of California, with the worst conditions (dark red) in much of the main agricultural region.

Image: U.S. Drought Monitor

California's drought will likely continue through 2015, regardless of a forecast El Niño event in the Pacific Ocean this winter, the study said; this is because such events don't guarantee a wetter-than-average winter in California's Central Valley region, where most of the state's agricultural production is generated.

Jay Lund, an engineering professor at U.C. Davis, said the fact that the current year is dry nearly doubles the chances that the following year will be, as well. “There is a very good chance that next year will be dry or critically dry,” he said.

The study found that the drought may not in fact cause consumer prices for fruit and vegetables to rise in the U.S., since that will be dictated by market demand, rather than the drought. California is the largest agricultural producer in the U.S., with nearly $45 billion in annual revenue.

The study was commissioned by the California Department of Food and Agriculture, whose secretary, Karen Ross, told reporters that efforts are underway to enact a new groundwater management system based at the local level.

Climate studies have shown that while this drought may have had mainly natural triggers, it is likely being exacerbated by warmer-than-average temperatures related to climate change. California has had its warmest year-to-date on record, after one of its warmest and driest winter seasons. Global-warming projections show a clear warming and drying trend in the southwest U.S., including parts of California.

Mashable
is a global, multi-platform media and entertainment company. Powered by its own proprietary technology, Mashable is the go-to source for tech, digital culture and entertainment content for its dedicated and influential audience around the globe.